spark plug color

[stock500]

what does this grey color mean?

[Hillclimb#42]

Indicates its been hotter than you want it. Either lean , preignition or wrong plug heat range or something causing it to burn hot. Tan/brown is right. Dry and dark brown is what I like.

[kaw rider]

piston melting, pull the head on look.

[stock500]

As far as running hot, I have a question.  I noticed when I stopped that my engine felt pretty hot, but my radiators were cold???  How do I check that my impeller is getting the flow it should. 

[KXcam22]

Stock,
  I you pull the rad cap with the engine cold and fire it up the flow should be evident.  Cold rads, warm engine is a strong inidcator that you are not any getting flow.  I recall one member who had the impeller spinning on the shaft.  Rare but can happen I guess.  The nylon pump drive gear could be a weak point, but then again after 14 years mine looked like new. I would suggest taking the water pump apart and inspecting. Also, definitely pop off the head and look at the piston crown.  Its hard to tell from the pic but there appears to be some deposits on the plug, possibly aluminum. Cam.

[Polar-Bus]

Yikes! Thats a lean burned plug.

I am not thinking it's lean from overheating, Maybe dirt in the carb partially blocking the main jet?

How about some more specific details as to how the engine was behaving before you pulled the plug???

I am hearing a TON of horror stories related to E10 based fuels sitting in engines for extended periods of time creating a skanky residue in carbs and fuel systems..

[stock500]

Cam thanks for the info.  I took a short ride tonight, and the radiator was warm on both sides.  I'm still going to look into the the flow while its running.  As far as fuel and the way the bike was acting.  I run pump gas and the bike still runs fine.  It has been hot as can be, but it runs fine.  The reason I'm replacing the piston is because I have very little compression.  I am going to fatten up the jetting this weekend, and give the carb a dang good cleaning.  Today after work I put in the NGK BPR8ES plug because the old one needed to be replaced.

[KXcam22]

Polar,
  I had bad experiences with Shell gasoline leaving a nasty green residue.  This was a few years ago, but the residue was impossible to remove with anything less than acetone.  I evaporated some in a jar and it was sticky like half dried paint.  I find nowdays that I run fuel stabilizer at all times just to be safe.  Low cost and keeps the paranoia away. Cam.

[Polar-Bus]

Polar,
  I had bad experiences with Shell gasoline leaving a nasty green residue.  This was a few years ago, but the residue was impossible to remove with anything less than acetone.  I evaporated some in a jar and it was sticky like half dried paint.  I find nowdays that I run fuel stabilizer at all times just to be safe.  Low cost and keeps the paranoia away. Cam.

E10 is getting to be a HUGE problem, especially in 2 stroke engines that sit dormant for long off seasons, such as snowmobiles, leaf blowers chain saws and such. I have been using an excellent product called Startron. It's specifically designed to combat E10 "phase separation" and excessive water in E10 fuel. All my 2 strokes have thus far run perfect.. The stuff is a bargain too, it's about $16, and treats 250 gallons

http://mystarbrite.com/startron//content/view/93/123/lang,en/